An Ultrastructural, In-Situ Study on the Impact of Desensitizing Agents on Dentin

Abstract

Introduction and aims: With the increasing prevalence of dentin hypersensitivity, more and more desensitizing agents with tubule-occluding properties are advocated in the market. The aim of the present study was to investigate the deposition of these agents on the dentin surface under in-situ conditions. Methods: Bovine dentin specimens were pretreated with phosphoric acid and fixed to individual upper splints that were carried by up to 2 subjects for 3 min to allow pellicle formation. The desensitizing agents containing either calcium carbonate and arginine, casein-phosphopeptide amorphous calcium phosphate, zinc-carbonate hydroxyapatite, tetracalcium phosphate and dicalcium phosphate anhydrous or hydroxyapatite nanoparticles were applied ex situ. Specimens without treatment served as controls. After a further 6 h of intraoral exposure, specimens were removed and analysed by scanning (n = 4 specimens per substance, in total) and transmission electron microscopy (n = 2 specimens per substance). Results: Application of desensitizing agents resulted in the deposition of different structures on the dentin surface and occlusion of dentinal tubules. Conclusion: The ultrastructural analysis using transmission electron microscopy indicates that dentinal tubules were occluded under in-situ conditions not only by inorganic but also by organic deposits from the oral cavity.